1. Field of the Invention
The present invention relates to a channel sharing method and device thereof, and more particularly, to a channel sharing method that ensures at least one transmitted signal of each channel is valid in the worst delay time and a device thereof.
2. Description of the Related Art
With the advancement of electronic and communication technology, wireless communication has been applied in various electronic products to enhance user-friendliness. In different states and areas, different channel ranges are used to avoid signal transmission collisions. Accordingly, the frequency range of each state or country is restricted. Each state or country has its own standard of wireless transmission, for example, assigned in the Industry, Science and Medical (ISM) band. Each state or country has different range and standard of ISM bands. Moreover, the available channels are far fewer than required. Accordingly, methods and apparatus to expand the channel numbers are sought after.
Generally, for the two-way wireless transmission or wireless control, such as the data transmission between cellular phones and base stations, the base stations control the transmission and receiving of the channel signals of all the cellular phones. Therefore, a restricted channel bandwidth can be extended that all the users can access the service with the cellular phones.
For the one-way wireless transmission or wireless control, for example, the signal transmission between a remote-controlled car and a remote controller, the remote controller controls the channels. Thus, when several remote-controlled cars are simultaneously operated, the collisions among the channels will occur, and some cars cannot receive the control signals for a long period of time.
FIG. 1 is a schematic drawing showing a multi-channel transmission of a conventional one-way wireless control. As shown in FIG. 1, channel 1 transmits signals 102, 104 and 106, the channel 2 transmits signals 112, 114, 116 and 118, and the channel 3 transmits signals 122, 124 and 126. The signal 102 collides with signals 112 and 122, and the signal 106 collides with signals 118 and 126, so that only signal 104 can be received by the receiver of channel 1. Likewise, for channel 2, only signal 116 can be received. For channel 3, no signal can be received.
In order to resolve the above issue in the one-way wireless control, one conventional method is to generate signals in each channel randomly. However, the time delay of each transmission between emitting and receiving of the signals cannot be estimated. Specially, when the channel number is increased, some channels are not able to receive signals for a long period of time.